Spark plug gap
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Launching!
Joined: Oct 2016
Posts: 248
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Spark plug gap Hello guys , I have a 5.3 single turbo and I don't plan on going any higher then 13 psi with 92 octane. I'm running NGK BR7EF.. they come with a .028 gap .. should I leave that gap alone or change it .. thank you in advance.
the boost and power output is low enough for you to experiment. Normally I would Try the larger gaps first (0.045~") , make sure you have a good voltage and battery and grounds etc... and hit it. If it blows out, it will be pretty obvious, and you can gap it down.
If you just want to skip all that then I would leave it 0.028"
Many will tell you they have run 15psi of boost on OEM 0.055" gaps
If you just want to skip all that then I would leave it 0.028"
Many will tell you they have run 15psi of boost on OEM 0.055" gaps
Leaving the stock tr7 Gap (.028) at that boost level. The power that you'd gain from a slightly larger Gap will be negated by the annoyance of it breaking up under boost and you chasing your tail. Nobody runs more than like .035 Gap in here in a boosted pump LS.
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Verdad Gallardo Thread Starter
Launching!
Joined: Oct 2016
Posts: 248
Likes: 1
Nothing lol. I believe you don't need to make a single 1/4 mile hit and pull the plug immediately to have a general idea what's going on with it. You can drive the car a bit and still see what the engine is doing with the plug.....but that thing is too far gone. You can see the timing mark on the strap but not sure I'd trust that. And you have so much fuel and carbon on the threads you cant get a good reading of the heat into the threads.
only thing I can say for sure is they should look much cleaner. After 20k they should still be sort of white-ish in some places if you tuned it open loop properly, or slight tan/white if you are using closed loop O2 control. The leanish cruise a/f ratio cleans up the plugs while you drive. the lip around (the circle part) will still be black but the center parts can be cleaned while driving at the right mixture.
here is a cheapy copper plug from an 122 cubic inch turbo engine @ 400rwhp, 93 octane (that would be like having 240 cubic inches at 800rwhp)
I drove approx 12k miles and checked:
nice and clean in the middle is a good sign. I ran it open loop 15.2:1 most cruise situations so its a bit whiter than you get when running closed loop.
The picture of the plug you posted looks like closed loop isn't working or the tuner has no idea what the a/f should be at idle and cruise.
here is a cheapy copper plug from an 122 cubic inch turbo engine @ 400rwhp, 93 octane (that would be like having 240 cubic inches at 800rwhp)
I drove approx 12k miles and checked:
nice and clean in the middle is a good sign. I ran it open loop 15.2:1 most cruise situations so its a bit whiter than you get when running closed loop.
The picture of the plug you posted looks like closed loop isn't working or the tuner has no idea what the a/f should be at idle and cruise.
Last edited by kingtal0n; Sep 3, 2017 at 10:51 AM.